Machine and method for rolling conical workpiece

ABSTRACT

A machine and method for rolling a conical workpiece is disclosed wherein relatively rotatable die means rotate a workpiece therebetween in planetary motion. A shoulder on one die urges the workpiece in one axial direction and a shoulder on the other die acts on the workpiece in an opposite axial direction to form roll thereon a crowned surface on the large end of the workpiece. The tilting or skewing of the workpiece relative to the dies helps establish this crowned end on the workpiece.

United States Patent 1 1 11 1 3,731,51 1 Matej et al. 1451 May 8, 1973 1541 MACHINE AND METHOD FOR 3,466,918 9/1969 Marcovitch ..72 91 ROLLING CONICAL WORKPIECE 2 $3,122 :32; 5 2? s s un lus Inventors: Ronald J- Matej, Farina; Edward 638,867 12/1899 Evans ..72/93 Prutton, Parma Heights, both f 1,446,447 2 1923 Bingham ..72/88 Ohio Primary Examiner-Lowell A. Larson [73] Assignee. gli'fitoton Corporation, Cleveland, Atwmey Louis v- Granger [22] Filed: Mar. 15, 1971 [57] ABSTRACT [21] App]. No.: 124,302 A machine and method for rolling a conical workpiece is disclosed wherein relatively rotatable die means [52] U 8 Cl 72/92 72/94 rotate a workpiece therebetween in planetary motion. I [51] ln.t.cl 821,. 1/14 A Shoulder on one die urges the workpiece in one [58] Field 89 90 axial direction and a shoulder on the other die acts on 72/91 the workpiece in an opposite axial direction to form roll thereon a crowned surface on the large end of the workpiece. The tilting or skewing of the workpiece [56] References cued relative to the dies helps establish this crowned end on UNITED STATES PATENTS the workpiece 2,410,312 10/ 1946 Storch ..72/92 31 Claims, 8 Drawing Figures 41-1: K I I MS I3 Patented May 8, 1973 2 Sheets-Sheet 1 w min N m u M N 2 2 A P 0 W W D MM we QE Y B Patented May 8, 1973 2 Sheets-Sheet 2 ENTORS. QONQLD J. ATEJ F. 8 BY EDWARD A. PRUTTON 4 TTORNE Y BACKGROUND OF THE INVENTION In forming tapered roller bearings, the several bearing elements are conical and roll between inner and outer races of the complete bearing. In order for the individual bearing elements of the complete bearing to support a proportionate share of the load, it is extremely important that the bearing elements be as nearly 1 equal in size as possible. It will be recognized that if one bearing element is larger than its neighbors then this larger one will take all the load and the neighbors will take little or none. Accordingly, in order to avoid cracking or crushing this bearing element, it has been found necessary to carefully size the bearing elements to within plus or minus ten millionths of an inch. This is a high degree of accuracy in repetitive forming of the various bearing elements during manufacture of the tapered roller bearing. Also in tapered roller bearing, a substantially radial shoulder on one race bears against the larger end of the conical bearing elements in order to support axial as well as radial loads. Hence, the dimensional tolerance, smoothness, shape and concentricity of the larger end is important.

In the past it has been customary to forge the bearing elements, harden them and then grind them to achieve the necessary dimensional tolerance and hardness. Such prior art methods, however, have been found lacking in the ability to consistently produce the bear ing elements to the desired dimensional tolerances because of continual wear on the grinding wheels.

Accordingly, an object of the invention is to provide a machine to form roll conical bearing elements for a tapered roller bearing.

Another object of the invention is to provide a machine and method to form roll a conical workpiece with a crowned larger end.

Another object of the invention is to provide a machine and method of form rolling a conical workpiece wherein the workpiece tilts slightly relative to the axis of the dies and this tilting action cold works the end of the workpiece to form a slightly crowned larger end on the workpiece.

SUMMARY OF THE INVENTION The invention may be incorporated in a machine for form rolling a conically tapered workpiece comprising, in combination, a base, die means on said base rotatable relative to said base, means including said die means to rotate in contact with a workpiece to roll form a conical periphery on the workpiece and to urge the workpiece in a first axial direction toward one end thereof, and means acting in an opposite axial direction to work on said one end of the workpiece near the periphery thereof.

SHORT DESCRIPTION OF THE DRAWING FIG. I is a plan view of a machine embodying the invention;

FIG. 2 is a side view ofa conical workpiece;

FIG. 3 is a sectional view on line 3-3 of FIG. 1;

FIG. 4 is a view on line 4-4 ofFIG. 3;

FIG. 5 is a view similar to FIG. 3 but with a modified die;

FIG. 6 is a view similar to FIG. 3 but with a further modified die;

FIG. 7 is a view on line 7-7 of FIG. 6; and

FIG. 8 is a perspective view of a tapered roller bearing utilizing the conical bearing element.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 illustrates a machine 11 which performs the preferred method for form rolling a conically tapered workpiece 12 as shown in FIG. 3. The machine 11 has a frame 13 having a motor 14 connected to rotate a spindle 15. The spindle 15 carries a rotary die 16 to cooperate with a stationary die 17. The rotary die 16 may be in the form of a continuous circular ring with one or more starts thereon, and the stationary die 17 may be an arcuate shoe clamped by clamps 18 to an adjustable die holder 20. This die holder 20 is held by adjusting screws 21 on the frame 13 which adjust the space between the dies 16, 17 at the entrance end 22 and the exit end 23 of the dies. This permits the workpieces 12 to roll in a planetary motion in this space between the dies from the entrance end to the exit end as the spindle rotates clockwise, as shown in FIG. 1.

A workpiece feed chute 25 is provided to supply workpieces to the entrance end 22 and a workpiece feed finger 26 reciprocates in guides 27 by means of a bell crank 28 driven from a rotating cam 29 on the spindle 15 to feed successive workpieces to the space between the dies. Other feeding arrangements may be utilized, this preferred embodiment having been found to operate quite satisfactorily to rapidly feed workpieces to the dies. The machine 11 may have a horizontal axis 31 of the spindle 15, or as shown in this preferred embodiment, the axis 31 may be vertical.

FIG. 3 illustrates a section through the rotating die 16 and the stationary die 17. FIG. 3 has been exaggerated in order to better illustrate the operation and shows the rotary die axis 31 much closer to' the die 16 than is the actual case and also shows the angle of the cone of workpiece 12 as exaggerated. In a practical machine constructed in accordance with the invention, the rotary die might be a ring 12 to 18 inches in diameter and would be a rigid ring to avoid deflection under the high rolling pressures. The stationary die shoe 17 would also be large and massive so as to resist the high rolling pressures. Also, an example of a conical work piece would be with the included angle being 330. Again, in FIG. 3, the angle of the cone is enlarged to better illustrate the operation of the machine 1 l.

The blank workpiece 12 shown in FIG. 2 prior to form rolling may often have a die flash 34 along a circumferential line caused by the mating line of the cold forging dies. This die flash may be removed by tumbling. The workpiece blank 12 :may also have an indentation 35 at the larger end and an indentation 36 at the smaller end of the cone. This blank workpiece 12 may be ground to establish a first limit of tolerances preparatory for the form rolling by the machine 11.

The die l6has a cylindrical first: surface 41v and the die 17 has a conical second surface between which the workpiece 12 is rolled in a planetary manner. A conical shoulder third surface 43 is provided on the rotary die 16 and a conical shoulder fourth surface 44 is provided on the stationary die 17. The cylindrical first surface 41 is a cylinder having the die axis 31 as the axis of the cylinder. The conical second surface 42 also has the spindle axis 31 as the axis of the cone. Accordingly, the apex 46 of the cone lies on the axis 31 of the rotary die 16.

In a practical die set made according to this invention, the conical workpiece has an included angle of 330 accordingly, this is also the angle of the conical second surface 42 relative to the axis 31. The conical shoulder third surface 43 had an angle of 145 or 2O' relative to a perpendicular to axis 31, and the conical shoulder fourth surface 44 had an angle of 145 relative to a perpendicular to axis 31.

Each of the surfaces 41 and 42 are surfaces of revolution and is formed by a generator moving around the axis 31. Line 47 may represent the generator of the circular first surface 41 and line 48 may represent the generator of the surface 42. These two generators intersect at a point 49 which is not at the apex 46 of the cone 42. The effect of this is to tilt or skew the workpiece 12 relative to the dies 16, 17. This tilting is shown in FIG. 4 where the rotation of the workpiece 12 is to the right as viewed in this figure. The top of the workpiece leans forwardly because the relative rotation between the workpiece 12 and rotary die 16 is rotation along a cylindrical surface rather than along a conical surface which theoretical cone would have an apex at the apex 46.

FIG. 8 illustrates the complete tapered roller bearing 51 in which the workpieces 12 may be used as individual conical bearing elements. Such roller bearing 51 has inner and outer races 52 and 53 and a substantially radial shoulder 54. The rolling surfaces of these two races are cones each having the same apex with this common apex on the axis of the entire bearing assembly. In such case, this is the proper shape for a roller bearing so that the individual bearing elements have no tendency to tilt or be skewed relative to the bearing axis.

Such construction of the bearing assembly illustrates the reason why there is a tilting of the workpiece 12 in the machine 11. As an example, the radius of the lower portion of the rotary die 16 is larger than the proper cone and consequently the large end of the cone attempts to rotate faster than the smaller end of the cone. Since the workpiece 12 is a unitary element, the two ends must rotate at the same rotational speed and, accordingly, the resulting action is to tilt the workpiece slightly as shown in FIG. 4. The larger end of the cone leans forwardly, that is toward the direction of travel of the workpiece 12 in its planetary motion. This tilting action means that the effective length of the workpiece between the shoulders 43 and 44 is increased. The conical shoulder fourth surface 44 acts as a locater surface preventing the workpiece from being forced downwardly and acts, further, as a means urging the workpiece 12 in a first axial direction toward one end thereof, namely, toward the larger end thereof. The conical shoulder third surface 43 on the rotary die is a means acting in the opposite axial direction to cold work this larger end of the workpiece near the periphery thereof. The axial position of the two dies 16 and 17 may be relatively adjusted in order to space apart the shoulders 43 and 44 the required dimension. The tilting action of the workpiece places a very large 7 larger end and the thrust shoulder 54 which is substantially radial on the inner race 52 of the bearing assembly 51. As is well known, a tapered roller bearing will support both radial and axial loads and the axial load is carried substantially longitudinally through the individual bearing elements 12 by this small contact area 58 on the thrust shoulder 54. Accordingly, it is extremely important to have this slightly crowned surface 55 at the larger end of the workpiece l2 and to have it smooth and substantially in a plane relative to the axis of the workpiece 12. The present method and machine 11 establishes this smooth hard uniform surface.

FIG. 5 illustrates a modified rotary die 16A and a stationary die 17A with first and second workpiece rolling surfaces 61 and 62 respectively. Both of these surfaces are conical with the cone 61 having an apex at 65 on axis 31 and the cone 62 having an apex at 66 on axis 31 which is non coincident with the apex 65. Because these apeces are not coincident, the workpiece 12 again does not roll correctly on the conical first surface 61, instead it tends to lean forwardly at the larger end, as shown in FIG. 4. Again, there is a tendency to tilt the workpiece 12 and the shoulders 63 and 64 will work the two ends of the workpiece into a slightly crowned shape.

FIG. 6 shows another embodiment of the invention witha rotary die 16B and a stationary die 178. The rotary die 168 has a first conical work-rolling surface 71 and the stationary die 178 has a second conical workrolling surface 72. The conical surface 71 has an apex on the axis 31 and the conical surface 72 has an apex 76, also on this axis but not coincident with apex 75. Because the apex 75 is closer to the dies than the apex 76, the workpiece 12, as it rotates relative to die 168, will tilt by leaning in the rearward direction relative to the direction of travel. Again the shoulders 73 and 74 will work the axial ends of the workpiece 12.

In FIGS. 3 and 5 it will be noted that the rotary die 16 has a working surface 41 or 61 which is a first surface of revolution having an angle relative to the axis of the second surface of revolution 42 or 62. Also, it will be noted in FIG. 5 that the apex 66 of the second surface cone 62 is closer to the dies than the apex 65 of the first surface cone 61. This is also true of FIG. 3, considering that the first surface 41 is a cone with an apex at infinity. Accordingly, in both FIGS. 3 and 5 the workpiece tilts in the same direction as shown in FIG. 4, namely, the larger end tips forwardly relative to the direction of travel.

In FIG. 6 the apex 75 of the first surface cone 71 is closer to the dies than the apex 76 of the second surface cone 72. Accordingly, this establishes the tilt of the workpiece as shown in FIG. 7, namely, the larger end leaning rearwardly relative to the direction of movement.

In FIG. 1 it will be noted that the stationary die 17 is adjusted by the screws 21 to have a substantially uniform thickness of space between the work rolling surface 41 and 42. However, in actual practice, the spacing at the exit end 23 of the dies is made slightly smaller in order to progressively cold work the workpiece 12 and to bring it to the desired dimensions.

The locater shoulder 44 which is an urging means is on one die and preferably the shoulder 43 is on the other die, with this shoulder being a means acting to work the end of the workpiece. These shoulders could be on just one of the dies but it is preferable to have them on opposite dies in order to be able to adjust the relative axial position of the dies for the desired longitudinal dimension of the workpiece 12.

The three FIGS. 3, 5 and 6 illustrate the method of using relatively rotating first and second dies to roll form the conical workpiece 12 with a rolled crown 55 on the larger end thereof. To accomplish this the workpiece is rolled between the dies in a planetary motion and there is established on the larger end of the work piece a force with a longitudinal and a lateral component. The tilting of the workpiece relative to the axis of the dies establishes a slightly longer effective length of the workpiece so that the shoulders 43 and 44 establish a lateral component of force. Also, the longitudinal component of force increases greatly during this tilting and the combined forces roll the slight crown 55 on the two ends of the workpiece In the complete bearing 51 it is the crown 55 on the larger end which is more important, but both ends are cold worked by this method and in this machine 11.

Although this invention-has been described in its preferred form with a certain degree of particularity, it is understood that the present disclosure of the preferred form has been made only by way of example and that numerous changes in the details of construction and the combination and arrangement of parts may be resorted to without departing from the spirit and the scope of the invention as hereinafter claimed.

What is claimed is:

1. A machine for form rolling a conically tapered workpiece comprising, in combination, a base,

die means including first and second dies with one thereof rotatable relative to said base,

afirst working surface on said first die having a first surface of revolution,

a second conical working surface on said second die having a second surface of revolution,

means including said working surfaces to rotate in contact with a workpiece to roll form a conical periphery on the workpiece and to urge the work piece in a first axial direction toward one end thereof,

means acting in an opposite axial direction to work on said one axial end of the workpiece near the periphery thereof,

the generatrix of said second conical working surface having an apex on the axis of the rotatable die,

and said first working surface being one of cylindrical and conical with the apex of the cone on the same side of said die means as the apex of said second conical surface and with the apices noncoincident.

2. A machine as set forth in claim 1, wherein said urging means includes a radially extending shoulder on said die means.

3. A machine as set forth in claim 1, wherein said acting means includes a radially extending shoulder on said die means. i

4. A machine as set forth in claim 1, wherein said die means includes a die stationary on said base.

5. A machine as set forth in claim 4, wherein there is a substantially uniform thickness of space around the periphery between said dies accomodating a workpiece therebetween rotating in planetary motion.

6. A machine as set forth in claim 4, wherein said acting means is on one of said dies and said urging means is on the other of said dies. v

7. A machine as set forth in claim 5 wherein said first die has a substantially cylindrical surface disposed to contact a workpiece.

8. A machine as set forth in claim 5 wherein said rotatable die has a substantially cylindrical first working surface to contact a workpiece and said stationary die has said conical second working surface cooperating with the first surface to roll the conical periphery of a workpiece therebetween.

9. A machine as set forth in claim 8, wherein said acting means includes a conical shoulder third surface on one of said dies to abut and form roll a crowned surface on the large end ofa workpiece by the action of the tilting of the workpiece relative to the axis of the cylindrical first surface.

10. A machine as set forth in claim 9, wherein said third surface is on said rotatable die.

11. A machine as set forth in claim 8, wherein said urging means includes a locator conical shoulder fourth surface on one of said dies to abut the smaller diameter end of a workpiece and to maintain the workpiece in engagement with said third surface.

12. A machine as set forth in claim 11, wherein said fourth surface is on said stationary die.

13. A machine as set forth in claim 1, wherein said first surface of revolution is conical.

14. A machine as set forth in claim 13, wherein the apex of said first surface coneis closer to the dies than the apex of said second surface cone.

15. A machine as set forth in claim 13, wherein the apex of said second surface cone is closer to the dies than the apex of said first surface cone.

16. A machine as set forth in claim 1, wherein said second surface cone has the apex thereof on said axis.

17. A machine as set forth in claim 1, wherein said first surface of revolution has an angle relative to said axis which is smaller than the angle relative to said axis of said second surface of revolution.

18. A machine as set forth in claim 1, wherein said first surface of revolution is substantially cylindrical.

19. A machine for form rolling a conically tapered workpiece comprising, in combination, a base,

die means on said base rotatable relative to said base,

means including said die means to rotate incontact with a workpiece to roll form a conical periphery on the workpiece and to urge the workpiece in a first axial direction toward one end thereof,

means acting in an opposite axial direction to work on said one end of the workpiece near the periphery thereof,

and said acting means includes means to tilt the axis of a workpiece relative to the axis of revolution of said die means.

20. A machine as set forth in claim 19, wherein said tilting means includes means to attempt to rotate the larger end at a speed different from the speed of the smaller end ofa workpiece.

21. The method of using relatively rotating first and second dies to roll form a conical workpiece and form a rounded crown on the larger end thereof,

comprising the steps of rolling the workpiece between the dies,

and establishing a force on the larger end of the workpiece with a longitudinal and a lateral component by tilting the workpiece relative to the dies by attempting to rotate the larger end of the workpiece at a speed different from that of the smaller end.

22. The method of using relatively rotating first and second dies to roll form a conical workpiece and form a rounded crown on the larger end thereof,

comprising the steps of rolling the workpiece between the dies,

establishing a force on the larger end of the workpiece with a longitudinal and a lateral component, providing a shoulder on the first die,

and utilizing said longitudinal component of force to direct the workpiece against said shoulder.

23. The method as set forth in claim 22, including providing a shoulder on the second die,

and maintaining the workpiece in engagement with both shoulders.

24. The method as set forth in claim 23, including tilting the workpiece relative to a die to establish said force. 7

25. The'method as set forth in claim 21, including forming one of the dies with a conical surface.

26. The method as set forth in claim 25, including forming the other of the dies with a substantially cylindrical surface.

27. The method as set forth in claim 25, including forming the other of the dies with a surface, the generator of which has the same axis as the cone but does not pass through the apex of the cone.

28. The method as set forth in claim 25, wherein the conical surface has an apex lying on the axis of rotation of one die.

29. The method as set forth in claim 28, including forming the other of said dies with a conical surface having an apex on said axis other than at said first mentioned apex.

30. The method as set forth in claim 29, including forming the other of said dies with a smaller radius than said one of said dies and with an apex closer to the dies than the apex of the cone of said one of said dies.

. 31. The method as set forth in claim 29, including forming the other of said dies with a smaller radius than said one of said dies and with an apex farther away from the dies than the apex of the cone of said one of said dies. 

1. A machine for form rolling a conically tapered workpiece comprising, in combination, a base, die means including first and second dies with one thereof rotatable relative to said base, a first working surface on said first die having a first surface of revolution, a second conical working surface on said second die having a second surface of revolution, means including said working surfaces to rotate in contact with a workpiece to roll form a conical periphery on the workpiece and to urge the workpiece in a first axial direction toward one end thereof, means acting in an opposite axial direction to work on said one axial end of the workpiece near the periphery thereof, the generatrix of said second conical working surface having an apex on the axis of the rotatable die, and said first working surface being one of cylindrical and conical with the apex of the cone on the same side of said die means as the apex of said second conical surface and with the apices non-coincident.
 2. A machine as set forth in claim 1, wherein said urging means includes a radially extending shoulder on said die means.
 3. A machine as set forth in claim 1, wherein said acting means includes a radially extending shoulder on said die means.
 4. A machine as set forth in claim 1, wherein said die means includes a die stationary on said base.
 5. A machine as set forth in claim 4, wherein there is a substantially uniform thickness of space around the periphery between said dies accomodating a workpiece therebetween rotating in planetary motion.
 6. A machine as set forth in claim 4, wherein said acting means is on one of said dies and said urging means is on the other of said dies.
 7. A machine as set forth in claim 5 wherein said first die has a substantially cylindrical surface disposed to contact a workpiece.
 8. A machine as set forth in claim 5 wherein said rotatable die has a substantially cylindrical first working surface to contact a workpiece and said stationary die has said conical second working surface cooperating with the first surface to roll the conical periphery of a workpiece therebetween.
 9. A machine as set forth in claim 8, wherein said acting means includes a conical shoulder third surface on one of said dies to abut and form roll a crowned surface on the large end of a workpiece by the action of the tilting of the workpiece relative to the axis of the cylindrical first surface.
 10. A machine as set forth in claim 9, wherein said third surface is on said rotatable die.
 11. A machine as set forth in claim 8, wherein said urging means includes a locator conical shoulder fourth surface on one of said dies to abut the smaller diameter end of a workpiece and to maintain the workpiece in engagement with said third surface.
 12. A machine as set forth in claim 11, wherein said fourth surface is on said stationary die.
 13. A machine as set forth in claim 1, wherein said first surface of revolution is conical.
 14. A machine as set forth in claim 13, wherein the apex of said first surface cone is closer to the dies than the apex of said second surface cone.
 15. A machine as set forth in claim 13, wherein the apex of said second surface cone is closer to the dies than the apex of said first surface cone.
 16. A machine as set forth in claim 1, wherein said second surface cone has the apex thereof on said axis.
 17. A machine as set forth in claim 1, wherein said first surface of revolution has an angle relative to said axis which is smaller than the angle relative to said axis of said second surface of revolution.
 18. A machine as set forth in claim 1, wherein said first surface of revolution is suBstantially cylindrical.
 19. A machine for form rolling a conically tapered workpiece comprising, in combination, a base, die means on said base rotatable relative to said base, means including said die means to rotate in contact with a workpiece to roll form a conical periphery on the workpiece and to urge the workpiece in a first axial direction toward one end thereof, means acting in an opposite axial direction to work on said one end of the workpiece near the periphery thereof, and said acting means includes means to tilt the axis of a workpiece relative to the axis of revolution of said die means.
 20. A machine as set forth in claim 19, wherein said tilting means includes means to attempt to rotate the larger end at a speed different from the speed of the smaller end of a workpiece.
 21. The method of using relatively rotating first and second dies to roll form a conical workpiece and form a rounded crown on the larger end thereof, comprising the steps of rolling the workpiece between the dies, and establishing a force on the larger end of the workpiece with a longitudinal and a lateral component by tilting the workpiece relative to the dies by attempting to rotate the larger end of the workpiece at a speed different from that of the smaller end.
 22. The method of using relatively rotating first and second dies to roll form a conical workpiece and form a rounded crown on the larger end thereof, comprising the steps of rolling the workpiece between the dies, establishing a force on the larger end of the workpiece with a longitudinal and a lateral component, providing a shoulder on the first die, and utilizing said longitudinal component of force to direct the workpiece against said shoulder.
 23. The method as set forth in claim 22, including providing a shoulder on the second die, and maintaining the workpiece in engagement with both shoulders.
 24. The method as set forth in claim 23, including tilting the workpiece relative to a die to establish said force.
 25. The method as set forth in claim 21, including forming one of the dies with a conical surface.
 26. The method as set forth in claim 25, including forming the other of the dies with a substantially cylindrical surface.
 27. The method as set forth in claim 25, including forming the other of the dies with a surface, the generator of which has the same axis as the cone but does not pass through the apex of the cone.
 28. The method as set forth in claim 25, wherein the conical surface has an apex lying on the axis of rotation of one die.
 29. The method as set forth in claim 28, including forming the other of said dies with a conical surface having an apex on said axis other than at said first mentioned apex.
 30. The method as set forth in claim 29, including forming the other of said dies with a smaller radius than said one of said dies and with an apex closer to the dies than the apex of the cone of said one of said dies.
 31. The method as set forth in claim 29, including forming the other of said dies with a smaller radius than said one of said dies and with an apex farther away from the dies than the apex of the cone of said one of said dies. 